The invention relates to a hydrogen fuel-cell power generator, and more particularly to a steam reformer (catalytic converter) using propane (or other hydrocarbon gas) as a source of hydrogen for the fuel cell with only CO and CO2 present that are easily removed before feeding the hydrogen to the fuel cell.
Although there has been significant research and development of fuel cells for power generation, both stationary as well as portable for automotive power, there are other significant needs for a portable fuel-cell power generation, such as aboard recreational vehicles (RVs) for nonautomotive applications, e.g., lighting, cooking, refrigeration, television and air conditioning. Most RVs are presently equipped with a propane system for some of these purposes and equipped with an electrical generator driven by a gasoline engine for other uses, including air conditioning.
A major problem with a gasoline powered generator is not only air pollution in and around a parked RV but also the noise disturbance they cause to others, particularly when run while in an RV park during summer nights. In a marine RV, such as a houseboat on a lake, the lake water is used to cool the engine stored in a compartment below deck where exhaust of that engine is known to accumulate. Besides noise pollution above and below deck, the engine exhaust presents life threatening pollution to those who may be sleeping below deck. Such air and noise pollution is also a disturbance to other RVs parked nearby.
The problem then is to provide an electrical power generation system that is free of air and noise pollution, such as a hydrogen fuel-cell system, but that solution has its own problem for both land and marine RVs. That problem is not only the need for storing a reasonable supply of hydrogen aboard, but also the problem of refueling at filling stations or marine docks. If hydrogen is stored aboard, it must be at high pressure, and that presents a high risk because hydrogen is highly flammable and explosive. One could use metal hydrides as a source of stored hydrogen, such as iron or titanium hydride from which the hydrogen is released at specified temperatures, but hydrides are themselves flammable and thus present a fire risk, more so because they react violently with water. In any case, such hydrides would not be as readily available at filling stations and marine docks as propane or methane, and propane is already being routinely stored in RVs and readily available at filling stations and marine docks.
In accordance with the present invention, a hydrocarbon gas fuel reformer comprising a cylinder packed with a commercially available and pelletized catalyst is used to react with the low pressure hydrocarbon gas and steam at a higher pressure to produce an exhaust rich in hydrogen with only carbon monoxide and carbon dioxide which can be easily removed before feeding the hydrogen to a proton fuel cell.
The low pressure hydrocarbon gas is introduced into the cylinder by a tube protruding a significant length (about 5 cm) into the cylinder through an end cap while steam under higher pressure is introduced into the cylinder through a tube positioned in the cylinder end cap near the fuel tube, but cut off inside the cylinder a length significantly less than the hydrocarbon gas tube, and preferably flush with the inside face of the end cap.
The high velocity of the steam past the end of the hydrocarbon gas tube draws low pressure fuel out of that tube and mixes that fuel with the steam to pass over surfaces of the pelletized catalyst over the length of the cylinder to an exhaust through a tube at the end cap of the opposite end of the cylinder.
The nearly pure hydrogen gas flowing through the exhaust tube under pressure is stripped of carbon monoxide and dioxide by conventional means in order to feed virtually purified hydrogen to the proton (hydrogen) fuel cell which produces electricity and steam exhaust. To assure the requisite reaction temperature in the cylinder, means for heating the cylinder from the outside is provided, preferably an electric or gas oven closed around the cylinder.
Energy present in the steam or hot water exhaust is utilized aboard the RV to reduce the energy required to produce the steam, to heat space in the RV if desired and other uses, such as to heat water for cooking and other purposes. In that manner, cogeneration of electric and thermal energy is simultaneously produced for an indicated potential fuel savings, as much as 30% with this fuel reformer. The catalysis that takes place between the streams of input steam and fuel is a reaction in which heat and hydrogen is produced with traces of carbon monoxide and some carbon dioxide, but without consuming the catalyst. The catalyst itself may thus remain in use in the cylinder for hundreds of hours.
The exhaust steam from the fuel cell is condensed for use in a variety of ways aboard the RV, including potable water after purifying it through a carbon filter on the way to storage in a main water tank. The electricity generated can also be used for a variety of purposes after converting it to the requisite voltage for each purpose through a conventional switching converter.
The novel features that are considered characteristic of this invention are set forth with particularity in the appended claims. The invention will best be understood from the following description when read in connection with the accompanying drawings.